High-potential rectifier.



L. W. CHUBB.

HIGH POTENTIALRECTIFIER. APPLICATION FILED JULY 12.1915.

Patented June 13, 1916.

1NVENTOR L e w/ls W C/wbb WITNESSES: v 7

ATTORNEY UNITED" sirATEs PATENT OFFICE.

LEWIS W. CHUBB, OF EDGEWOOD PARK, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

HIGH-POTENTIAI: RECTIFIER.

Patented June 13, 1916.

" Application filed July 12, 1915. Serial No. 39,419.

To all whom it may concern:

Be it known that I, LEWIS W. CHUBB, a citizen of the United States, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have invented a new anduseful Improvement in High-Potential Rectifiers, of which the following is a specification.

tain in systems employed for causing the deposition of finely divided particles of'matter originally held in suspension in bodies of gas or-vapor, by the application of electric charges. Moreover, my rectifiers may be utilized for exciting Rontgen-ray and similar tubes, and also for other service which may require the application of high-potential electric discharges.

For the service conditions indicated, and more especially for separating suspended particles from gaseous bodies, it is desirable to operate at such voltagesas will effect elec trical discharges. To illustrate, for, the special service cited above, it is preferred to produce silent electrical non disruptive discharges or corona emanations'. In accordance with the principles disclosed in U. S. Patent No. 1,067,974 to F. G. Cottrell, it is desirable to maintain a non-disruptive discharge at maximum potential through the gaseous bodies to be precipitated, the negative potential being applied preferably at the surface from which the corona. discharges emanate and being of such a value as to be in excess of that which may be maintained when the positive potential isapplied to the said surface. Consequently, the discharge surface is maintained at a very high negative potential in order to produce corona:

or silent electrical discharges in one direction only.

Inasmuch as it is difficult to acconiplish the aforementioned result by applying a direct-current voltage of the requisite potential, the desired result has heretofore been obtained by employing an alternating-current high-potential transformer in combination with a rectifier which, in practice, has been almost without exception, a mechanical rectifier. The difiiculties involved in the operation of mechanical rectifiers for such high-voltage service are numerous and well known, and, as a substitute therefor, I propose to employ a rectifier of the character disclosed in this invention. While these rectifiers need be of relatively small power capacity only, it is essential that they be adequately insulated in order to successfully withstand such voltage stresses as, of necessity, will arise from the high electrical potentials utilized in the system. Again, a compact and simple structure is preferred because ofthe low initial cost and the small amount of attention required for inspecting the apparatus. For the accomplishment of these ends, and for other objects which will be hereinafter pointed out, I have invented an electrolytic rectifier, the characteristic features of which will be fully pointed out in the following description andthe accompanying drawing in which' I Figure 1 is a view, somewhat diagrammatic, of a smoke precipitating system employing an electrolytic rectifier constructed in accordance with my invention, and Figs. 2 and 3 are cross-sectional views, taken at right'angles to one another, of a, portion of my electrolytic rectifier.

As mentioned above, the smoke-precipitating device shown at 1 utilizes high-potential voltages which will effect electrical .discharges in one direction only. To obtain such electrical discharges, an electrolytic rectifier- 2 embodying my invention is interposed between the smokeprecipitator l and smoke stack 10. The smoke stack 10 is pro- Hit? tifier. A specific form of minum and vided with an inlet 11 through which the gaseous body and with an outlet 12 through which the gaseous body, after having its suspended particles removed therefrom, is emitted. As mentioned above, the conductor 7 emits negative corona .discharg'es which, in turn, impart electrical charges to the particles held in suspension in the gaseous body to be precipitated. By means of the rectifier 2, the conductor 7 is continuously subjected to a negative potential of such a value that a non-disruptive discharge is effected, the

potential difference between the negative conductor 7 and the positively charged smoke stack 10 being in excess of that which can be maintained when the positive potential is applied to the discharge conductor 7. Consequently, it will be understood that the potentials impressed upon the smoke precipitator 1 must, of necessity, be very high in value and,-to this end, the electrolytic rectifier 2 must be so designed as to safely and expeditiously rectify the high-potential alternating currents generated by the highpotential transformer 3,

In constructing the electrolytic rectifier 2, the several elements which are subjected to potentials of varying values are so disposed with respect to one another that the external electrostatic field generated will enhance the insulating properties of the recmy rectifier may A be constructed by drilling several strips of 35 insulating material 13 with a plurality of equally. spaced holes 14 of the character shown in Figs. 2 and 3. Theholes 14 constitute containing chambers for liquid bodies 15 which comprise any suitable electrolyte.

Extending between adjacently disposed holes 14 and being immersed in the electrolyte 15, are metallic elements lfiwhich comprise a film-forming metal 17 such as alua non-film-forming metal 18 such as lead, the two metals being intimately united in any suitable manner as, for instance, by means of a percussive weld. The elements 16 extend between adjacent cells 14, as shown, eachcell comprising an aluminum electrode and a lead electrode which are separated from one another by. the intervening body of electrolyte 15. The rectifying action of cells of the character described is well known, the current freely passing from the lead electrodes 18 through the electrolyte 15 to the aluminum electrodes 17, but the im edance oifered by the films formed onsai aluminum electrodes to a reversal of the aforesaid flow of current precludes the current from flowingin the o posite direction. The electrolyte 15 whic I prefer to employ in my electrolytic rectifier 2 may be of the character disclosed in my c0-pending patent application, Serial No. 864,666, filed October 2, 1914 and assigned to the to be precipitated is admitted tial transformer 3.

. the current Westinghouse Electric and Manufacturing Company. I have found this electrolyte to be particularly durable and efficacious and capable of forming films on the aluminum electrodes 18 of high resistivity.

According to the electrolytes employed, and the electrodes comprising the individual electrolytic cells 14, I may form films on the film-forming electrodes which will resist from 280 to 400 volts. As a consequence thereof, it will be apparent that a number of cells 14 connected in series relationship must be employed in order torectify the highpotential alternating currents generated in the secondary winding 6 of the high-poten- Consequently, each of the'insulating strips 13 comprise a plurality of electrolytic cells 14 which are connected in series relationship with one another, as hereinbefore explained. The potentials impressed upon the cells 14 embodied in each strip 13 will vary in value from one another by equal amounts, providing the cells 14 are identical in structure, as is presumed.

The rectifier 2 comprises four strips 13 which are equal in length and arranged in a. rectangular or square formation, as shown in Fig. 1. To insure the desired electrostatic field formation, corresponding cells 14 of oppositely-disposed strips.13 are to lie on the same imaginary elements which, for convenience, may be called the potential elements of the external electrostatic field resulting from the potentials impressed upon the several cells 14. Assume that a positive impulse is impressed upon the rectifier 2. In this instance, the terminal 19 of the secondary winding 6 momentarily assumes a positive potential, and current will traverse a conductor 20 in the direction indicated by the arrow a.

Inasmuch as a terminal21 is ofaluminum,

is precluded from flowing through the series of cells 14 comprising the branch 13. of the rectifier 2, but, since an adjacently disposed terminal 22 is formed of lead, the current may flow through the group of cells 14 comprising the branch 13" of the rectifier 2, as indicated by thearrow a. The current, after having traversed the cells comprising the arm 13", flows alon a conductor 23 from a terminal 24 inasmuc 1 as an adjacently'disposed terminal 25 is formed of aluminum and, consequently, precludes the flow of current through the group of cells comprising the branch 13 of the rectifier. the smoke precipitator 1 is charged to a positive potential, the discharge or negative electrode 7 thereof being charged to a Asa result, the electrode 10 of 55 precipitator 1, the electrical conditions obtaining being similar to those explained charge electrode 7 and the terminal 25 of l the highpotential secondary winding 6, which terminal momentarily assumes the negative potential, may be traced in a manner similar to that hereinbefore explained with reference to the flow of the charging current to the positive electrode 10.

Since the branches 13 and 13 of the rectifier' 2 are simultaneously utilized for the current flow to the smoke precipitator 1, during a positive wave impulse in the secondary winding 6 of the transformer 3, corresponding cells 14 have impressed thereupon the same potentials; for instance, a cell 26 of the branch 13 assumes the same potential as a cell 26 of the branch 18, and a cell 27 of the branch 13 assumes thesame potential as a cell 27 d of the branch 13, and so on. In order toinsure a uniform distribution of the electrostatic field, it is essential that the cells 26 and 26 and the cells 27 and 27 and the other pairs of corresponding cells which are impressed with equal potentials, be so disposed with respect to one another" that they lie on the same imaginary potential elements-of the external electrostatic field arising from the positive wave impulse impressed upon the rectiof cells is disposed assumes the highest potential of the external electrostatic field. To assist in understanding. the distribution of the external electrostatic field, I have employed lines 29 to represent'the imaginary potential elements of the external electrostatic field, and, by varying the shades of the .lines' 29, I have indicated the gradations of the potentials of the elements comprising the external electrostatic field, the heavy line 30 indicating the element of highest potential.

When a negative impulse is impressed upon the rectifier 2, the branches 13 and 13 of the rectifier 2 are utilized for conducting the charging or corona currents to the smoke above. In this instance, however, the imaginary element of highest potential of the external electrostatic field may be represented by a line 31 which is at right angles to the elements 29 of the external electrostatic field generated during a positive impulse. larly, all of the imaginary elements which are represented by the lines 32 constitute Y apparent that uniform distributions of the the metallic element 16,- bein Simithe external electrostatic field which is generated when a negative impulse is impressed upon the rectifier 2.

From the foregoing description it will be external electrostatic fields are insured by so disposing the individual electrolytic cells 14 .that those which momentarily and simultaneously assume corresponding potentials will lie on the same elements of the recurrently-generated electrostatic fields resulting from'the positive and negative impulses im' arted by the generator 5.

n Fig. 1, the arrOWs a indicate the direction of current flow when positive impulses so are lmpressed upon the rectifier 2, and the arrows Z) indicate the direction of current flow when negative impulses are impressed thereupon. As a result, the conductor 7 a of the smoke precipitator 1 is continuously g5 subjected to negative potentials of such values as will most effectively precipitate the suspended particles in the gaseous body admitted to the smoke precipitator. Moreover, the electrolytic cells 14 of the rectifier 2 are $0 disposed with respect to one another, and the branches 13, 18 13 and 13 of the rectifier 2 are so arranged that the external electrostatic fields-greatly enhance the insulating properties of the rectifier 2.

It will be noted that the metallic ele- "ments 16 are so designed that their arched portions extend beyond the upper surface of the insulating strips 13, 13", 13 and 13.

In this manner, the electrolytic cells 14 may be conveniently and ex editiously filled with electrolyte without a ecting the insulating properties of the rectifier 2; for instance, inasmuch as the cells 14 are relatively small in size, all of the cells comprising a single strip 13 may be filled by pouring a body of electrolyte over the insulating strip. Each cell 14 will then be filled to the level of the insulating strip, and the'arche d portions of the upper face of the strip, w1ll not come in contact with the electrolyte.

While I have shown my invention as applied to an electrolytic rectifier of the type herein disclosed, it will be apparent to those skilled in the art that the principles embodied herein may be utilized with equal effectiveness in insulating high-potential rectifiers comrising a group of rectifiers of any form, each of which is subjected to arelatively small potential only. It will'be understood, therefore, that many modifications may be made without departing from the spirit and scope of the appended claims.

I claim as my invention:

1. A rectifier for alternating currents comprising a plurality of individual cells or rectifiers arranged in groups which are so disposed with respect to one another that the cells subjected to corresponding poten- 13 spaced from 11o tial increments between currents comprising a plurality of individual electrol tic cells arranged in groups which are similarly disposed in parallel relation to one another in order to effect a uniform distribution of the external electrostatic field resulting from the potentials impressed on the several cells.

4. An electrolytic rectifier for alternating currents comprising a plurality of individual electrolytic cells arranged in groups, the cells comprising each group be-- 1ng connected in series relationship and the severalgroups being so disposed with re-.

spect to one another as to generate a uniform external electrostatic field.

5. An electrolytic rectifier for alternating currents comprising a plurality of similar and individual electrolytic cells arranged in groups, the cells of each group being connected in series relationship, and the potenadjacently-disposed cells being uniform, the said cell groups being so arranged as to effect a uniform distribution of the external electrostatic field. 6. The combination with an electrical device comprising a plurality of asymmetric conductors arranged in groups, the asymmetric conductors in each group being-connected in series relationship, of means to impress high voltages upon said electrical device whereby the several asymmetric elementsmay assume potentials that vary in value from one another by equal amounts,

said several groups being so disposed with respect to one another as to effect a uniform distribution of the external electrostatic field.

7. The combination with an electrical device comprising a plurality of asymmetric conductors arranged in groups, the asymby equal amounts,

the recurrently genmetric conductors of each group being connected in series relationship, of means for impressing high voltages upon said electrical device whereby the several asymmetric conductors of each group may assume potentials that vary in value from one another said several groups being so disposed with respect to one another that the asymmetric conductors subjected to corresponding potentials will lie on the same potential elements of. the external electrostatic field.

8. A high-potential alternating-current rectifier comprising a plurality of asymmetric conductors arranged in groups, the asymmetric conductors of each group being connected in series relationship and the several conductors being so disposed with respect to one another that those of corresponding potentials will lie on the same potential elements of the external electrostatic field.

9. A high-potential alternating-current and the asymmetric conductors in each group being connected in series relationship, said several groups being so disposed with respect to one another as to effect a uniform distribution of the external electrostatic field.

10. The combination with an alternating-current rectifier comprising a plurality of individual rectifiers arranged in groups, the rectifiers of each group being connected in series relationship, and means for impressing thereu on highpotential alternating currents, o a device requiring voltage discharges in one direction only interposed between the several groups, said several groups being so disposed with respect to one another that the individual rectifiers of corresponding potentials may lie on the same potential elements of the external electrostatic fields.

In testimony whereof, I have hereunto subscribed my name this 28th day of June,

LEWIS W. CHUBB. 

